For many years salt has been spread along a roadway during the winter season to remove ice and reduce the tendency for skidding by vehicles travelling along the roadway. In more recent years, the salt has been spread by a rotating spreader which centrifugally discharges salt dropped on the spreader from a dump bed carried by a truck or other vehicle moving along the roadway. The most successful devices of this nature have involved an elongated hopper extending along the discharge end of the dump bed and including a lower rotating auger which moves the salt toward one end of the hopper. At this end, there is a discharge opening which discharges or drops salt from the hopper onto the spinning broadcast spreader. This general combination is now widely used in spreading salt along a roadway. Such a hopper is very beneficial during use as a spreader; however, if the truck is to be used to dump salt or other material directly onto the roadway in a wide path the hopper has to be removed. To overcome this difficulty, it was proposed that the hopper include a movable cover plate, as shown in Swenson U.S. Pat. No. 3,189,355. The cover plate is moved into a vertical position for spreading and is then shifted to a horizontal position to allow dumping of material over the hopper. Although the structure of this patent is not commonly used, the concept of providing a cover having a vertical position for spreading and a horizontal position for dumping is quite common in salt spreaders. Other patents showing this feature are Daneman U.S. Pat. No. 3,349,970 and Buchmann U.S. Pat. No. 3,438,585. Although a movable cover which could be moved between a dumping position and a spreading position was widely used, this type of structure still presented serious difficulties. Salt being spread would often clog in the auger, especially if it became damp or was allowed to sit for a prolonged time in the hopper. Consequently, it had been proposed that the hopper be provided with a means for allowing access to the auger for cleaning. Such an arrangement is shown in Swenson U.S. Pat. No. 3,510,066. In this patent, the rear wall of the hopper is pivotally mounted so that it may be dropped for cleaning access to the auger extending longitudinally along the lower portion of the hopper. This type of structure allows cleaning by a water hose, etc. and utilizes a movable upper cover shiftable between two positions and a removable rear wall for cleaning. These patents discussed herein are incorporated for reference for the purpose of background information.